A wide variety of firearms are known in the art. Some are highly focused to achieve a particular characteristic at the expense of others (e.g., target rifles are extremely accurate, but fairly easy to damage or knock out of alignment). Others are designed to perform well in a broader range of situations, while not excelling at any particular task. Some configurations are widely implemented, albeit with varying sizes and assembly details, so that a user of one such firearm can disassemble, reassemble and use a different firearm of the same design, even though the individual pieces of the two firearms may not be interchangeable. The popular 1911-style semiautomatic pistol is one such design. Finally, some designs are produced to comprehensive specifications such that the individual components are compatible and can be mixed-and-matched between different firearms, different manufacturers, and even different eras. The Armalite “AR-15” is an example of this last type.
Owners of common/compatible firearms often change or upgrade certain components to adapt the guns to the owner's particular application. For example, an AR-15 may be fitted with a longer barrel and high-magnification scope for use in target competitions. Some common customizations improve a firearm's utility for left-handed users.
AR-15 semi-automatic rifles (as well as some similar platforms such as M-4 and M-6 rifles) use a charging handle (also called a “cocking handle” or “bolt handle”) to manually operate the action, for loading the first round from a new magazine (subsequent rounds are automatically loaded when the action cycles after a previous round is fired). They can also open the action for unloading (and for confirming that the firearm is unloaded), or to clear a jam or misfire. Thus, charging handles are a critical component of a firearm, notwithstanding that they are usually employed much less often than once per round fired. Improvements to the charging handle can help a gun operate more smoothly and reliably, and can make it easier for the user to shoot. FIG. 8 shows a left-side view of a typical AR-15 rifle, with the approximate location of the charging handle indicated by a dashed rectangle, and the direction of operation of the handle indicated by a heavy arrow.